Supraglottic tubes are tubes inserted into the pharynx to keep open the airways and to ventilate a patient. A classic example is a so-called larynx mask. By means of the tube a larynx mask is introduced through the central pharynx via the epiglottis into the lower pharynx and placed behind or around the larynx. Such larynx masks are used to ventilate a patient who is anaesthetised. They allow the insertion of tubes, probes, optical instruments and other instruments into the airways. At the same time larynx masks can have an oesophageal access. This allows the introduction of probes into the oesophagus and the stomach in order to remove gastric juices and other fluids as well as air from the stomach. In anaesthetised patients emptying of the stomach is intended to prevent the stomach contents flowing back into the upper respiratory tract and being aspirated into the unprotected airways (windpipe, bronchi and lungs). A further advantage of an oesophageal access is the removal of passively or actively regurgitated stomach contents from the upper oesophagus to outside, which thereby represents limited, and thus inadequate, aspiration protection.
A large number of different larynx masks are known on the market. A typical example is set out in U.S. Pat. No. 5,878,745. This shows a gastro-laryngeal mask in which the supraglottic tube is a pipe through which several tubes can be fed. These tubes have lumens which are used for ventilation and for an oesophageal access.
The combination of a larynx mask with an oesophageal passage is becoming more and more available. U.S. Pat. No. 7,040,322 also shows such a larynx mask and the supraglottic tube here is divided by means of an intermediate wall running ventral-dorsally wherein in the larger of the two lumens produced by the division a separate tube is inserted which is used to inflate or deflate a proximal area of the larynx mask.
A larynx mask with a relatively rigid supraglottic tube can be introduced more easily, whereby the rigidity of the supraglottic tube prevents adaptation of the position of the larynx mask to the anatomical conditions. Insertion into the pharyngeal cavity by means of a relatively rigid supraglottic tube can result in injury, and positioning in the pharyngeal cavity is not always reliable.
Highly flexible larynx masks tube (PROSEAL LMA®, FLEXIBLE LMA®) allow better positioning in the larynx but are more difficult and therefore occasionally more traumatic to insert and more difficult to position in the pharynx.
In the last decade anatomically curved supraglottic tubes for inserting the larynx mask have proven themselves. They not only allow simple introduction of the larynx mask into the pharynx and good positioning, but they also exhibit better sealing. Such larynx masks with a rigid, curved tube are used particularly in emergency situations. Due to the anatomically preformed shape they can also be inserted by paramedics in emergencies.
Typical examples of such larynx masks are sold under the name LMA FASTRACH® (U.S. Pat. No. 5,896,858) and LMA CTRACH®, both by the company LMA Inc. However, because of their rigidity these bent supragottic rigid tubes cannot be left in the patient over a longer period of time and are not therefore suitable for the routine treatment of patients.
A similar design is also supplied by the company Ambu GmbHl, whereby the version is sold under the name AMBU AURA 40™. The curve angle of the supraglottic tube is however greater and wider and the tube softer in consistency. The latter allows this larynx mask to be used routinely over longer periods.
Particularly when an intervention in the neck and head area has to take place, the position of the head can vary greatly and accordingly a larynx mask with a preformed relatively rigid tube can hardly be used. However if the larynx mask is correctly positioned on the larynx fixing in such position is desirable.
To increase the sealing of the larynx mask on the larynx, the “Proseal patent” (GB 9 821 771) describes a dorsal cuff which on the highly flexible supraglottic tube pushes the larynx mask away from the posterior wall of the pharynx and onto the larynx.
Finally a larynx mask is known from US 2007/0028923 with a supraglottic tube in which a further lumen is formed in the wall of the respiration lumen for passing through a cord as simple traction means. The traction means grips the distal end of the larynx mask whereby it is also bent. Controlled and active resetting is not possible.